Low pressure taps for flat

[YorkshireMidge]

I'm refurbing a flat, where the cold/hot water tanks are on the same floor, so I reckon I'm looking at not much more than 0.1bar on hot (and bath cold, which is also gravity fed as there is a shower mixer on the bath - though the flow is rubbish so only suitable for washing your hair really). Raising the tank isn't an option. Heating is all electric.

Are there any nice contemporary taps and bath/shower mixers out there that GENUINELY work on 0.1 bar? I've found some Bristan ones that work on 0.2 but struggling to find anything lower.

My fall back plans are:

1. Switch bath cold to mains, pump the hot with a Grundfos Home Booster pump, and fit a thermostatic bath/shower mixer.

2. As above but fit a proper electric shower, rather than a bath shower mixer (this is going to be a pain as it will mean a new consumer unit etc + its setup for Economy 7 so this will mean more expensive daytime tarif).

3. Go the whole hog and fit a direct/unvented cylinder, and a thermostatic bath/shower mixer.

Thoughts on pros and cons of these also appreciated!

 

[Madrab]

Even if they do work, the flow at that pressure will always be lousy anyway. If you want to get flow enough to give you a good shower then it's either the pump with the associated noise but cheaper solution to - with suitable mains pressure and flow - installing a direct unvented solution for mains pressure hot and cold water but with a larger installation cost.
Either solution will always have an expensive overhead when direct hot water needs boosted later in the day, if a shower is required.
An Electric shower is point of use so you only pay for what you use but the electrical upgrade can sometimes be more than the shower & they can be a pain in the winter with the colder incoming mains.

 

[YorkshireMidge]

Thanks Rob - I think you've helped me make my mind up that I need to do something. I have no idea of the age of the existing copper cylinder but it certainly LOOKS like its been there an awful long time, so I think swapping it for an un-vented is probably the better way to go.

Reading up, the only problem is the discharge pipework is going to be a complete nightmare because of the position of the airing cupboard, one room in from the nearest outside wall + concrete floor + 2 floors up!

 

[Madrab]

In the 1st instance, would recommend that you get someone in who has their UHW (G3) qualification to spec out an un-vented and see if location will be suitable and that a suitable safety outflow could be installed, also get them to test the water pressure/flow to ensure that your supply is adequate for an un-vented.

 

[YorkshireMidge]

Well, having studied the regs, and studied where the pipework would have to go, I think I can rule out un-vented without needing any specialist's input to confirm it

So looks like I'm lumbered with a pump solution, but I also want a thermostatic bath/shower mixer for safety reasons which means balancing the input, but the cold water pressure is reasonably high in the flat.

So what I'm planning on doing is putting a Grundfos 15-90 on the hot at the tank, which will give 0.5-0.75bar on top of the existing 0.1bar pressure, and switching bath cold to mains, and fitting a PRV local to the bath with a 0.5bar upwards rating so I can balance the booster pump without taking the whole flat pressure down that far and hitting problems with anything that might struggle below 1 bar such as washing machine. Check valves added too etc.

This won't give a fantastic shower flow out the mixer but it might just be adequate.

Anyone any thoughts on this?